1. Field of the Invention
The invention lies in the field of conveying technology and relates to a device and to a method for collating two-dimensional objects. The invention may in particular be applied for forming stacks of products lying on one another; such a stack formation for example is a step with the manufacture of printed products which consists of several part printed products and other products such as e.g. CDs, product samples and other things, e.g. newspapers, magazines, brochures, books and likewise.
2. Description of Related Art
The collation of printed products is understood by the man skilled in the art as the placing of different printed products onto one another, into stacks. Usually, the same printed products lie on one another in the same sequence in all stacks. The stacks may however, as the case may be, also differ from one another by way of the fact that individual printed products are absent in individual stacks. The printed products are for example individual, unfolded or folded sheets or signatures which are folded several times. The printed products which are collated into a stack differ from one another with respect to their printed content, but may however also differ with regard to their shape.
Known devices for collating printed products comprise a plurality of conveyer compartments which are moved along a conveying path. Usually, several feed units are arranged along a collation and stretch along the conveying path, and these are designed for feeding printed products of a single type. The exits of the feed units which are directed towards the conveyor compartments are essentially arranged one after the other in a row, whose direction corresponds to the conveying direction of the compartments along the collation stretch. In each case, one compartment is aligned onto, in each case, one feed exit during the feed steps. The feed units are for example feeders, reel stations or on-line connections to devices, in which the printed products to be collated are created or processed.
In collation devices, in which the printed products are fed to the compartments essentially perpendicularly to the conveying direction, usually the compartments are stationary during the feed steps and the printed products are pushed or thrown from the side into the compartments which are directed onto the feed exits. Between successive feed steps, the printed products with the compartments are displaced by the distance between consecutive feed exits (or by an integer fraction of this distance), in a manner such that the compartments aligned onto the exits are replaced by compartments following these. The compartments of such a device are usually arranged in a manner such that the printed products lay therein horizontally or in a slightly sloping manner. Disadvantages exist in the necessary intermittent stop- and go operation of the conveying means for the compartments.
Collation devices with compartments moving in an essentially continuous manner in the collation direction do not have these disadvantages. The printed products, however, must be essentially equally aligned with the collation direction and must be pushed or thrown into the compartments in a manner which is exactly synchronised with these compartments, wherein their speed is also to be adapted to the conveying speed of the compartments, for feeding the printed products to continuously moving compartments without any problem. The compartments, for example, are formed by a conveyor belt with separating walls which are arranged transversely and, as the case may be, also longitudinally to the belt length, wherein in each case two adjacent transverse walls delimit a compartment. The fed printed products are stacked in a lying manner on the conveyor belt in these compartments. Further known collation devices with continuously conveyed compartments have V-shaped or L-shaped compartments, in which the fed printed products stand on an edge and lean on a compartment wall, as a rest surface/support surface, which leads or trails in the collation direction.
A collation device with compartments which are L-shaped in the longitudinal section in the conveying direction and which are moved through the collation region by a conveying member along a closed revolving path, is known from WO 2007/085101. The longer compartment wall which is orientated essentially horizontally in the collation region, serves as a rest surface for the objects, and the shorter compartment wall which is essentially vertically orientated in the collation region, serves as an abutment, on which the leading edges of the objects are aligned. The compartments are arranged in a pivotable manner relative to the conveying member. Their pivot position is controlled such that the orientation of the rest surface in space remains constant independent of the shape of the conveying path, and specifically with a slight inclination in the conveying direction. In this manner, it is possible for the stacks to remain lying in the rest surfaces without them being actively held, even with a change of the conveying direction, e.g. in curved sections of the conveying path.
A further collation device is known from WO 2008/058405, with which the walls of all compartments are defined by continuous belts which run around deflection means. By way of the zigzag-like deflection along the conveying path, the belts open out a plurality of compartments which are L-shaped in section and which are directly consecutive to one another without interruption. The orientations of the side walls of adjacent compartments may be set in dependence on one another, by way of changing the position of the deflection means (rollers, rods). The long side wall, for example, is inclined relative to the conveying path or to the conveying member, and the short side wall is orientated in an essentially vertical manner, so that an oblique rest surface and an abutment which projects upwards from this are formed. In an alternative configuration, the two side walls are orientated parallel to the conveying path and may enclose a stack between them. By way of this, it is possible to convey the stack also with a rest surface which is arranged in a steep manner or above the stack (upside down). The orientation of the side walls of adjacent compartments, however, may not be selected independently of another, since the belts run over the mentioned common deflection means, so that the angle of inclination of the rest surface and the opening angle between the side walls are coupled to one another.
A further collating conveyor is known from DE-A 31 45 491. It comprises a plurality of grippers, wherein the rest surface which is assigned to a gripper, for supporting the laid-on products, is formed by the upwardly pointing gripper jaw of the gripper leading in the conveying direction. With this, the inclination angle of the rest surface and the opening angle of the grippers are likewise not independent of one another. The inclination is moreover opposite to the conveying direction.